# From which fundamental force do centrifugal and centripedal force arise? **URL:** \ **Category:** Factual Questions\ **Created:** [November 2, 2006, 6:22pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874 "2006-11-02T18:22:21Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Sattua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sattua/32/11906_2.png) [@Sattua](https://boards.straightdope.com/u/Sattua)\ **Post date:** [November 2, 2006, 6:22pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/1 "2006-11-02T18:22:21Z")
Gravitational or electromagnetic? And how? Feel free to discourse on other forces while you’re at it. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 2, 2006, 6:40pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/2 "2006-11-02T18:40:47Z")
I’m afraid you misunderstand the term. Centripetal force is the fotrce thatr must be applied to make an object move in a circle. It isd always directed toward the center of rotation. It can bwe gravitationasl, as when planets go around the sun or moons around planets. It can be electromagnetic, as with electrons around a nucleus. It can be in the form of a rope attached to the weight I’m rotating around me in a circle. The “Centripetal” refers to how the force is used and its direction, not its origin. > **[Centripetal force](https://en.wikipedia.org/wiki/Centripetal)** > > A centripetal force (from Latin centrum, "center" and petere, "to seek") is a force that makes a body follow a curved path. The direction of the centripetal force is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre". In the theory of Newtonian mechanics, gravity provides the centripetal fo One... “Centrifugal” force is a “fictitious force” experienced in a rotating reference frame that seem to direct everything _away_ from the center. You experience it when you’re in a car that rounds a curve, for instance. It’s not that the effects of the force aren’t real, but that the force isn’t really the result of an applied acceleration – it’s due to your assumption that your reference frame (the interior of the car) is actually inertial. Your body stubbornly insists on trying to continue to move forward when the car turns. There isn’t any force on it until you start pressing on the door of the car, and the “centrifugal force” is what would have to be applied to you in a truly inertial frame in order for you to feel the force you seem to feel. Complicated, huh? ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [November 2, 2006, 6:41pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/3 "2006-11-02T18:41:43Z")
Neither. You CAN use gravity or magnetism to generate a centripedal force, but neither are required. And centrifugal force is merely an artifact of measuring within an accelerating reference frame. It’s really just plain old inertia. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 2, 2006, 6:54pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/4 "2006-11-02T18:54:31Z")
Centripetal force can be any sort of force at all: In an orbit, the centripetal force is gravity, and if you’re twirling a ball on a string around your head, then the centripetal force is the tension in the string, which is ultimately due to electromagnetism. The term “centripetal” describes what the force happens to be doing (causing something to move in a circle), not what causes it. Centrifugal force is what’s called a fictitious force, and only appears because you’re in a non-inertial reference frame. It has the same formula as centripetal force, but it’s not the same thing: You don’t have centripetal and centrifugal force in the same reference frame. A centrifugal force is not exerted by anything, and is therefore not an example of any of the four forces. However, in Einstein’s theory of general relativity, gravity itself is also a fictitious force, and results from the same sort of reference-frame shenanigans as does centrifugal force, so if you wanted, I suppose you could put centrifugal force into the “gravity” category. ---
**Author:** ![Sattua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sattua/32/11906_2.png) [@Sattua](https://boards.straightdope.com/u/Sattua)\ **Post date:** [November 2, 2006, 6:55pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/5 "2006-11-02T18:55:56Z")
Thanks, everybody. Physics is so… bloody… depressing. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [November 2, 2006, 7:14pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/6 "2006-11-02T19:14:25Z")
> [@](#): > > Physics is so… bloody… depressing. Why _depressing_? The fact that you can explain everything, and calculate the results so neatly is, to me liberating and exhilarating. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [November 2, 2006, 7:36pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/7 "2006-11-02T19:36:09Z")
[QUOTE=Pochacco] Neither. It’s really just plain old inertia. [/QUOTE] Right. When you are thrown to the outside of the turn in a car it’s just because you are a more or less loose particle in the car and you tend to keep going in a straight like while the car turns under you. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [November 2, 2006, 8:19pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/8 "2006-11-02T20:19:44Z")
[QUOTE=CalMeacham] Why _depressing_? The fact that you can explain everything, and calculate the results so neatly is, to me liberating and exhilarating. [/QUOTE] Well, using physics you can predict everything but the more you know the less it explains. Gravity, fer example. We can model in wonderful detail how two masses attract each other gravitationally but still don’t have the faintest idea why it happens. We can model it all mathematically and talk about warped space and such but when it comes right down to it we just don’t understand it. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 2, 2006, 8:29pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/9 "2006-11-02T20:29:16Z")
Define “understand it”. Personally, I think I understand gravity a heck of a lot better than I understand most things in life. What more do you want to “understand”? You want to know some things I genuinely don’t understand? Love. The beauty of a sunset or rainbow. Laughter. But none of those things are depressing. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [November 2, 2006, 9:47pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/10 "2006-11-02T21:47:22Z")
[QUOTE=Chronos] Define “understand it”. Personally, I think I understand gravity a heck of a lot better than I understand most things in life. What more do you want to “understand”? You want to know some things I genuinely don’t understand? Love. The beauty of a sunset or rainbow. Laughter. But none of those things are depressing. [/QUOTE] Heading for GD here but love is similar. I can describe love as an evolved adaptation, chemical reactions in the brain, etc., but have no idea why we experience it the way we do. I can describe the behavior of gravity exactly with all the equations but still have no idea why two masses attract. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [November 2, 2006, 11:59pm UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/11 "2006-11-02T23:59:03Z")
I can’t remember who linked [this](http://xkcd.com/c123.html) the last time centrifugal/centripetal force was discussed, but I like it. ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [November 3, 2006, 12:16am UTC](https://boards.straightdope.com/t/from-which-fundamental-force-do-centrifugal-and-centripedal-force-arise/378874/12 "2006-11-03T00:16:42Z")
[QUOTE=CookingWithGas] Heading for GD here but love is similar. I can describe love as an evolved adaptation, chemical reactions in the brain, etc., but have no idea why we experience it the way we do. I can describe the behavior of gravity exactly with all the equations but still have no idea why two masses attract. [/QUOTE] Nor do we know why like electrical charges repel each other, or like magnetic poles. And do we know why there even are two different polarities of charges? In fact, I don’t think we know why any of the fundamental constants are what they are. But, so what?